Nonwoven fabrics are well known in the art and are popular for use in the medical field. Doctors commonly wear masks and gowns made from nonwoven fabrics, and operating and diagnostic rooms are typically equipped with drapes, towels and the like which are made from nonwoven fabrics. In order for such items to be suitable for use in a surgical environment they should be strong to resist rupture and have good electrical conductivity to prevent the build-up of static electricity and hence the sparking resulting from the discharge of static electricity. Conductive fabrics which reduce sparking are particularly desirable in a surgical environment because sparking poses a danger of explosion when pure oxygen is used in the operating room.
In this regard, it is known in the art to treat nonwoven fabrics with conductive agents to render the material conductive and thereby reduce the build-up of static electricity. This is typically accomplished by spraying or otherwise applying an aqueous solution of a conductive agent onto the nonwoven material after it has been formed and then drying the material by passing it over steam cans to remove the residual water. One example of such a process is shown in U.S. Pat. No. 4,379,192 to Walquist et al. and assigned to Kimberly-Clark Corporation, the assignee of the present application. Conventional application methods which apply the conductive agent to the formed material and which require subsequent drying of the material need improvement because drying a nonwoven material to remove residual water is detrimental to the strength and hand of the material.
It is also known to apply a conductive agent to nonwoven fabrics using conventional printing methods. Printing allows the conductive agent to be applied without the need for additional drying steps; however, printing is not a commercially feasible method for applying conductive agents because it does not provide a uniform concentration of the agent at the high line speeds of modem material producing operations.
Accordingly, there is a need in the art for a method of applying a conductive agent to a nonwoven material in a commercial operation which does not require subsequent drying of the material and therefore does not decrease the strength and other qualities of the material.